Question about Flat Panel Televisions
I notice a bunch of blue dots al over my 42 plasma tv , how can b fix
SOURCE: Samsung Plasma TV
I have been having the exact same problem. TV on for 30 min with terrible static, then all of a sudden it is perfect again. I've also inherited a bit of a humming noise from the tv as well. It was suggested to me in this forum to have a tech come and adjust the v_scan and v_set settings down a few mhZ. No idea what this means, but I assume it's a power setting and the tech will be able to take care of this. I will post my results when i have the tech in.
Posted on Jan 15, 2008
SOURCE: red and green dots
This post is basically for anyone that stumbles across it trying to fix what seems like two fairly common problems with plasma tvs. I apologize for the length of it but hope it can help others.
To start off, I got a free Audiovox FPE4216P 42" Plasma TV.
The previous owner said that there was a red cloud in the top center that after time spread across the top and down the center of the screen. Some time later, they were watching it and it was as if someone simply turned the power off. After that, there was no longer any picture - menu or otherwise.
After much research on the net, it seems that fixing plasma TVs is strongly based on the educational guess method. This compounded by the fact that replacement parts are quite scarce and generally crappy customer service provided by the manufacturer if the TV is older than 14 months basically makes many of these TVs $2000 doorstops if something goes wrong with them. Luckily, my TV uses many LG boards which seem to be used in a number of different makes and models.
NO DISPLAY ISSUE:
Once I took the set apart, I first checked the power coming into it and it checked out ok. I then found a fuse on the YSUS board that had blown, upon replacing it, I no longer had sound. The indicator light on the front would turn from red to blue for about 3 min then back to red. After this happened, the LED on the power board would light up and the there was no longer any response from the power button (led on front would only stay red). I would have to unplug the set and plug it back in to duplicate the above.
I then checked the voltages for Vs, Va and 5v on the connectors coming off the power board (using the DC setting on a voltmeter) against the specs on the sticker on the back of the display panel and they checked out.
It was recommended that I change the YSUS board since the fuse had blown on that board. This seemed counter-intuitive to me since it seemed that the power was fed into the YSUS board through that fuse first as if to protect the YSUS board.
With reluctance, I purchased a "new" YSUS board. Once I popped it in - presto! I had picture! But picture with a cloudy, sparkly red "I" beam that would show through the dark areas of images including the menu screens. It seemed that as long as there was a color over where the "I" beam ran, it was fine and there was only a problem when the image was supposed to be black.
RED DOTS - SPARKLES - SPECKLES - and possibly MAL DISCHARGE ISSUE:
I say possibly mal discharge because it seems that some label this problem as such where some describe mal discharge as another problem.
After much research on the net (again), it seems that there are two fixes for this problem: 1 - a new control board and 2 - adjusting the voltages. It seems that each fix has about a 30 - 50% success rate. With the first fix, you just pop in a new board and you could be done or you could have the same problem. With the second fix, people have said that the dots have gone but the image is now crappy or they have different color dots. Some also say that merely changing voltages will only temporarily fix it. I opted for the cheaper second fix.
My power board has two potentiometers (pots) on it (adjustable dial thingies). One for the Vs and one for the Va. I first made sure that these were adjusted to spec. I took readings off of the molex connector and grounded to the support bracket of the set.
My YSUS board has 4 pots, two are labeled SetUp and SetDn and the other two are on little circuit boards rising off the YSUS board - one of which was completely inaccessible due to it's position behind the support bracket.
I first set the TV to an empty input since the red showed best against all black. Jacking up the SetUp pot seemed to have the effect of making the black really black and essentially removing the red. SetDn didn't seem to due much and I didn't mess with the other pots. When I switched to an active source everything looked great but then I started to notice that on bright images that weren't quite white, there was blotchy pixelation and redness. It then started messing with all three accessible pots and got the image to be really good but I could still see some red and now blue sparkles in the dark areas.
I was pretty satisfied with my results but there was that one other pot that I could not get to unless I removed the YSUS board. Since I knew I would have to adjust that pot multiple times, I decided to remove the board and drill a small hole in the support bracket to gain access to the pot with the board installed. For me, this was the most difficult and frightening part. I didn't want to damage the panel itself and I also didn't want to get metal shavings everywhere. I carefully masked off the area and nearby boards with paper and when I drilled I held a piece of wood behind the bracket.
I then had access to all 4 pots and just kept messing with different balances between them. I used an empty input to check the black and numerous DVD's to look for crappy picture on lighter areas. As it turns out, the menu for the Underdog DVD really showed the light image flaws.
Now, the image is about 98% perfect. When a lighter image turns to complete black, there are some, extremely diffuse red and blue brief pixel flashes (just for a millisecond) but then the black stays black. To notice it, you have to be within 3 or 4 feet of the TV which I think is too close anyway for a 42" TV and is virtually non-existent when watching DVDs.
Here is some extra part number info with possible equivalents:
YSUS: 6871QYH953A or 6870qyh005B and possibly 6871QYH053B EAX31974801 EBR31872801 EBR32642701 6870QYH105B EAX31631001 EBR32642702 1032298-hs
Control Board: 6871qch977b or 6870qch0C6b and possibly 6870qch006b 6871QCH077B 5070-5623
Power Supply Board: 667-PH42FB6-20 or 782-PH42D8-200a and possibly 6FB0192010
Posted on Jun 21, 2008
I have a VPW450HD set that I just fixed. I get the feeling that they are not all the same inside, but this may be the same problem many of you are having. When turned on the green light on the front of the set would come on, if in a dark room I could see that there was some light to the screen ( not much ) but no picture and no sound. When I pushed the power button to turn the set off - it would not turn off. I had to turn it off from the main power switch on the back.
If you take the back off you will see a large square board in the center of the TV ( about 12" X 10" ). I would describe this as the main power supply board. Near the top there is a two wire connector with a Red & Black wire in it. Follow this wire up to the next board. It is a smaller board ( about 5" X 3" ) with the Red & Black wire connector near the top right corner. I would describe this board as a secondary power supply board. It sends the power down to the input board. On the secondary power supply board there is a six connector plug on the left side of the board. This is where I found the problem with mine. The connector is burnt and melted because of a " cold solder " joint. Carefully remove the secondary power supply board - you may be able to use the same connector if it is not to burnt and brittle. The six pins on the solder side of the board need to be re-soldered. These pins are thicker material than the other solders, and so do not solder well in a wave solder process. the pins do not get hot enough to solder properly, so over time an opening is created between the pin and the board.
Make sure you do not change the order of the wires if you have to replace the connector or if you solder the wires directly to the board. If you use the same pins and connector - check that they will make good contact. Often there is a residue on the pins and the small clips in the connector. I took the wires out of the connector and cleaned them ( one at a time ) with a small wire brush. A razor blade also cleans them well.
I hope this helps some or all of you !
Let me know if it worked for you or if you have questions.
Posted on Jan 06, 2009
that is called diffusion. that can be adjusted out in most cases by adjusting the y sustain pcb but can also be the main pcb, the logic pcb and panel itself but not likely.
Posted on Jan 11, 2009
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